RANS Based Calm Water Resistance Prediction for Tumblehome Hull With Different Bow Appendages

2019 ◽  
Author(s):  
Shuzheng Sun ◽  
Xin Zhao
Keyword(s):  
Flow Field ◽  
Test Data ◽  
Model Test ◽  
Water Resistance ◽  
Grid Size ◽  
Time Step ◽  
Submerged Body ◽  
Calm Water ◽  
Calculation Results ◽  
Resistance Prediction

Abstract The calm water resistance of the models a bare tumblehome hull and with 3 different bow appendages (triangle fins, rectangular foil, and semi-submerged body) are predicted based on RANS and k-ε turbulence model using STAR CCM+ software. VOF method is used for the 2-phases simulation. The resistance calculation results of the bare hull are validated against model test data. The verification and convergence studies are carried out on the grid size and time step. The validation studies show that the relative changes of the resistance calculation results compared with the model test data for Fr = 0.294 are 5–6%. The results of resistance prediction for the hulls with 3 bow appendages show that the bow fin configuration shows the best performance at Fr = 0.220, and the semi-submerged body configuration shows the best performance at Fr = 0.367. The details of flow field of different hulls will be analysed in this paper.

Guidelines for CFD Simulations of Spar VIM

2013 ◽  
Author(s):  
Charles Lefevre ◽  
Yiannis Constantinides ◽  
Jang Whan Kim ◽  
Mike Henneke ◽  
Robert Gordon ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Test Data ◽  
Model Test ◽  
Model Tests ◽  
Full Scale ◽  
Mooring System ◽  
Time Step ◽  
Cfd Simulations ◽  
Scaled Model ◽  
Sway Motion

Vortex-Induced Motion (VIM), which occurs as a consequence of exposure to strong current such as Loop Current eddies in the Gulf of Mexico, is one of the critical factors in the design of the mooring and riser systems for deepwater offshore structures such as Spars and multi-column Deep Draft Floaters (DDFs). The VIM response can have a significant impact on the fatigue life of mooring and riser components. In particular, Steel Catenary Risers (SCRs) suspended from the floater can be sensitive to VIM-induced fatigue at their mudline touchdown points. Industry currently relies on scaled model testing to determine VIM for design. However, scaled model tests are limited in their ability to represent VIM for the full scale structure since they are generally not able to represent the full scale Reynolds number and also cannot fully represent waves effects, nonlinear mooring system behavior or sheared and unsteady currents. The use of Computational Fluid Dynamics (CFD) to simulate VIM can more realistically represent the full scale Reynolds number, waves effects, mooring system, and ocean currents than scaled physical model tests. This paper describes a set of VIM CFD simulations for a Spar hard tank with appurtenances and their comparison against a high quality scaled model test. The test data showed considerable sensitivity to heading angle relative to the incident flow as well as to reduced velocity. The simulated VIM-induced sway motion was compared against the model test data for different reduced velocities (Vm) and Spar headings. Agreement between CFD and model test VIM-induced sway motion was within 9% over the full range of Vm and headings. Use of the Improved Delayed Detached Eddy Simulation (IDDES, Shur et al 2008) turbulence model gives the best agreement with the model test measurements. Guidelines are provided for meshing and time step/solver setting selection.

Three-Dimensional Large Amplitude Body Motions in Waves

2007 ◽  
Author(s):  
Xinshu Zhang ◽  
Robert F. Beck
Keyword(s):  
Free Surface ◽  
Three Dimensional ◽  
Surface Boundary ◽  
Forward Speed ◽  
Time Step ◽  
Surface Boundary Conditions ◽  
Submerged Body ◽  
Calm Water ◽  
Wigley Hull ◽  
Constant Strength

Three-dimensional, time-domain, wave-body interactions are studied in this paper for cases with and without forward speed. In the present approach, an exact body boundary condition and linearized free surface boundary conditions are used. By distributing desingularized sources above the calm water surface and using constant-strength panels on the exact submerged body surface, the boundary integral equations are solved numerically at each time step. Once the fluid velocities on the free surface are computed, the free surface elevation and potential are updated by integrating the free surface boundary conditions. After each time step, the body surface and free surface are regrided due to the instantaneous changing submerged body geometry. The desingularized method applied on the free surface produces non-singular kernels in the integral equations by moving the fundamental singularities a small distance outside of the fluid domain. Constant strength panels are used for bodies with any arbitrary shape. Extensive results are presented to validate the efficiency of the present method. These results include the added mass and damping computations for a hemisphere. The calm water wave resistance for a submerged spheroid and a Wigley hull are also presented. All the computations with forward speed are started from rest and proceed until a steady state is reached. Finally, the time-domain forced motion results for a modified Wigley hull with forward speed are shown and compared with the experiments for both linear computations and body-exact computations.

Calm-Water Resistance Prediction of a Surface-Effect Ship

2009 ◽  
Author(s):  
Kevin J Maki ◽  
◽  
Lawrence J Doctors ◽  
Riccardo Broglia ◽  
Andrea Di Mascio ◽  
...  
Keyword(s):  
Water Resistance ◽  
Surface Effect ◽  
Calm Water ◽  
Surface Effect Ship ◽  
Resistance Prediction

Numerical Analysis for Resistance Calculations of NPL as a Floating Hull for Wave Glider

2014 ◽  
Vol 619 ◽  
pp. 38-43 ◽  
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng ◽  
H. Elhanfey
Keyword(s):  
Numerical Analysis ◽  
Mesh Generation ◽  
Numerical Scheme ◽  
Water Resistance ◽  
Numerical Predictions ◽  
Calm Water ◽  
Resistance Prediction ◽  
Wave Glider ◽  
Solution Parameters ◽  
Good Agreement

Thewave glideris an autonomous unmanned vehicle (AUV) which uses the power of the ocean to propel itself. The purpose of this study is using the well known slender modelNPLin developing hull in an attempt to design the floating hull ofwave glider.CFDandMaxsurfsoftware are used to present a method focused on mesh generation to predictcalm water resistancefor the hull. Calculations are carried out for Froude numbers in the range of 0.10 to 0.40. Three different mesh sizes are used forCFDto calculate the mesh effects. The results of numerical predictions under the same conditions obtained fromCFDandMaxsurfcalculations are obtained and compared for accuracy of the solution parameters. The comparison shows a good agreement between the results. The method is useful and acceptable and the overall numerical scheme is suitable for resistance prediction.

scholarly journals Effect of water resistance on predictions of ship ice resistance using towing tests in ice basin

2021 ◽  
Vol 4 (398) ◽  
pp. 43-52
Author(s):  
Kirill Sazonov ◽  
◽  
Grigory Kanevsky ◽  
Mikhail Lobachev ◽  
◽  
...  
Keyword(s):  
Test Data ◽  
Model Test ◽  
Hydrodynamic Interaction ◽  
Water Resistance ◽  
Test Results ◽  
Improved Method ◽  
Towing Tank ◽  
Ice Floes ◽  
Ice Resistance

Object and purpose of research. The object under study is a method to determine ice resistance using towing tests of ship models. The purpose of the work is to develop a method that takes into account the water resistance effect on predictions of full-scale ship ice resistance. Materials and methods. The materials for development are model test data and earlier methods for determination of ice resistance on models, as well as recommendations of the International Towing Tank Conference (ITTC). Main results. The method is suggested to take into account the water resistance in analyzing the towing test data obtained in the ice basin, as well as the method for extrapolating the ice resistance due to hydrodynamic interaction of ice floes with underwater hull, including the scale effect. Conclusions. The methods that take into account the water resistance effect on predictions of ship ice resistance based on towing test data obtained in ice basins are reviewed and analyzed. An improved method to include the water resistance effect in a more correct way is suggested. For better comparison of test results in ice basin it is required to introduce a common method of including the water resistance effect using the method suggested in this work.

scholarly journals Numerical Simulation of Resistance Field of Hull-Propeller-Rudder Coupling

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Hong Xie ◽  
Baoji Zhang
Keyword(s):  
Numerical Simulation ◽  
Body Force ◽  
Water Resistance ◽  
Wave Resistance ◽  
The Body ◽  
System Model ◽  
Force Method ◽  
Body Force Method ◽  
Calm Water ◽  
Calculation Results

Based on the incompressible RANS equation, the KVLCC1 ship's resistance field's numerical simulation is carried out. In this paper, the bare hull (calm water resistance and wave resistance) and hull-propeller-rudder models are studied and compared with the values of the Hydrostatic resistance test. In the hull-propeller-rudder system's performance analysis, the body force method is used to replace the real propeller model. The new calculation domain is set for the hull-propeller-rudder system model and meshed again to obtain the highly reliable numerical simulation results. Finally, the calculation results are analyzed. The research results in this paper can provide technical support for the resistance of similar ship types.

Benchmark Study on Thruster-Hull Interaction on a Semi-Submersible Crane Vessel

2011 ◽  
Author(s):  
Harald Ottens ◽  
Radboud van Dijk ◽  
Geert Meskers
Keyword(s):  
Test Data ◽  
Model Test ◽  
Numerical Study ◽  
Open Water ◽  
Model Tests ◽  
Complex Flow ◽  
Calculation Results ◽  
Thrust Efficiency ◽  
Force Components ◽  
The Individual

During offshore heavy lift or pipelay operations the station keeping capabilities of a DP-vessel have an important influence on operability limits of these operations. Heerema Marine Contractors has two DP3-class semi-submersible crane vessels for these operations; the Thialf and Balder. An assessment of the thrust efficiency of the DP thrusters of these vessels has been made by comparing CFD computations with dedicated model tests. A numerical study using CFD is performed to assess thruster-hull interaction on a semi-submersible vessel. The CFD results are validated with a series of model tests, including an open water thruster, single thruster-hull interaction without current and full thruster-hull interaction with all thrusters active without current. The CFD calculation results show good agreement with the model test data. The forces on the semi-submersible as well as on the individual floaters with active thrusters using CFD are within 10% of the model test data. The largest discrepancies are in the bow quartering conditions when the thruster-hull interaction show the most complex flow pattern due to the location and shape of the stern keel. The comparison between the CFD and model test data demonstrates that CFD is able to predict the relevant force components well within a sufficient accuracy for engineering purposes. The paper also addresses lessons learnt to improve the CFD computations as well as practical aspects and limitations of thrust efficiency modeling using CFD from an engineering perspective.

scholarly journals Calm Water Resistance Prediction of a Container Ship Using Reynolds Averaged Navier-stokes Based Solver

2017 ◽  
Vol 194 ◽  
pp. 25-30 ◽  
Author(s):  
Hafizul Islam ◽  
Md. Mashiur Rahaman ◽  
Hiromichi Akimoto ◽  
M. Rafiqul Islam
Keyword(s):  
Water Resistance ◽  
Navier Stokes ◽  
Container Ship ◽  
Calm Water ◽  
Resistance Prediction ◽  
Reynolds Averaged Navier Stokes
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